What should this chord be?

I'm trying to learn a Jason Reeves song called Pretty Eyes. The song
is in the key of E major. At some points in the song he does a
chromatic walk down from the C#m to the C to the A maj. At some
points, instead of hitting the C, he hits the B major. This is easy to
play and sounds good, but I'm trying to figure out how to do that
little chromatic walk down instead. By the way, these are all barre
chords. And I'm playing the C#m starting on 4th fret A string...not
9th fret E string. I've tried keeping my fingers in the same position
and lowering the root now (basically moving the tip of my pointer
finger a fret), but that just sounds bad. How should I play this
chord? Or this walk down? Kudos to any who understood this question :)